microchip: lan865x: fix missing netif_start_queue() call on device open

microchip: lan865x: fix missing netif_start_queue() call on device open

This fixes an issue where the transmit queue is started implicitly only
the very first time the device is registered. When the device is taken
down and brought back up again (using `ip` or `ifconfig`), the transmit
queue is not restarted, causing packet transmission to hang.

Adding an explicit call to netif_start_queue() in lan865x_net_open()
ensures the transmit queue is properly started every time the device
is reopened.

Fixes: 5cd2340cb6a3 ("microchip: lan865x: add driver support for Microchip's LAN865X MAC-PHY")
Signed-off-by: Parthiban Veerasooran <parthiban.veerasooran@microchip.com>
Link: https://patch.msgid.link/20250818060514.52795-2-parthiban.veerasooran@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>